Open AccessA large intracellular pool of inactive Na channel alpha subunits in developing rat brain.
Author(s) -
John T. Schmidt,
Sandra Rossie,
William A. Catterall
Publication year - 1985
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.82.14.4847
Subject(s) - intracellular , immunoprecipitation , protein subunit , biology , biochemistry , biogenesis , microbiology and biotechnology , phosphorylation , g alpha subunit , alpha (finance) , gene , medicine , construct validity , nursing , patient satisfaction
An intracellular pool of Na channel alpha subunits has been detected in developing brain cells in vivo and in vitro by phosphorylation with cAMP-dependent protein kinase, immunoprecipitation with specific antiserum, and NaDodSO4 gel electrophoresis or by radioimmunoassay. These alpha subunits are membrane-bound, contain complex carbohydrate chains, and have an apparent molecular weight of 260,000 like mature alpha subunits. In contrast to mature alpha subunits, the intracellular subunits are not covalently attached to a beta 2 subunit, and they do not bind saxitoxin with high affinity. They comprise 67-77% of the total immunoreactive alpha subunit in developing rat brain cells but are not a prominent component in the adult brain. It is proposed that this intracellular pool of alpha subunits forms a ready reserve of preformed subunits for incorporation into the surface membrane during periods of active membrane biogenesis. The results suggest that disulfide linkage of the alpha and beta 2 subunits, insertion into the cell surface membrane, and attainment of a functional conformation are closely related late events in the biogenesis of the Na channel. These processes may regulate the number of functional Na channels in the developing brain.